New Low-Temperature Performance-Grading Method: Using 4-mm Parallel Plates on a Dynamic Shear Rheometer
29 Oct 2011-Transportation Research Record (Transportation Research Board of the National Academies)-Vol. 2207, Iss: 2207, pp 43-48
TL;DR: In this article, an alternate mechanical test to the bending beam rheometer (BBR) was proposed to determine low-temperature PG using 4mm-diameter parallel plates on a dynamic shear rheometry (DSR) and includes a correction for machine compliance.
Abstract: Mechanical measurements on asphalt binders to determine the performance grade of the low-temperature specification are typically carried out with a bending beam rheometer (BBR). The BBR test requires considerable material to fabricate a specimen (approximately 15 g per beam). The relatively large amount of asphalt binder required for the BBR limits its applications. The BBR is difficult to apply to extracted asphalt binder or to other situations in which there is a limited amount of binder, for example, residue from emulsions. This paper proposes an alternate mechanical test to the BBR to determine low-temperature PG. Only approximately 25 mg of asphalt binder are required to perform a test. The test employs 4-mm-diameter parallel plates on a dynamic shear rheometer (DSR) and includes a correction for machine compliance. This correction allows testing to -40°C. A low-temperature specification from the 4-mm rheometry is suggested by the establishment of a correlation between BBR creep stiffness data and DS...
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TL;DR: In this article, the authors investigate the field aging effect on binder rheology and structure and establish the structure-rheological property relationships with the ultimate goal of predicting rheological properties of field aged binders.
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TL;DR: In this paper, a failure criterion for the fatigue testing of asphalt binders under cyclic loading in the dynamic shear rheometer is proposed. But the failure definition is material-dependent and is effective in capturing the benefits of asphalt modification for binder fatigue resistance.
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TL;DR: In this paper, the effect of polymer modification on the dynamic rheological properties at low temperatures was investigated using the 4-mm DSR technique and fluorescence microscopy and temperature-modulated differential scanning calorimetry.
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References
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TL;DR: In this article, two new approximation methods for treatment of viscoelastic data are introduced: relaxation (or retardation) spectrum is obtained from several values of the real (or imaginary) component of the complex modulus (or compliance) without differentiation.
171 citations
TL;DR: In this article, a new technique using 4-mm parallel plates on a dynamic shear rheometer (DSR) with machine compliance corrections was developed to measure low-temperature properties of asphalts.
Abstract: A new technique, which uses 4-mm parallel plates on a dynamic shear rheometer (DSR) with machine compliance corrections, was developed to measure low-temperature properties of asphalts. Good results have been achieved at test temperatures as low as -40°C. The test method requires only about 25 mg of material instead of 15 g for the bending beam rheometer (BBR). Also, no specimen premolding is needed, and a relatively low temperature (60°C to 70°C) is required to load the samples into the measuring system. The key to the new technique is correction for errors due to machine compliance. Two types of machine compliance correction were applied to the dynamic frequency sweep data in this work. The following areas were investigated: effects of machine compliance on the measured low-temperature properties, reproducibility of data, consistency among data collected on different sizes of plates after machine compliance corrections, and comparison between the corrected data from DSR and converted BBR data. Results s...
91 citations
TL;DR: In this article, a simple method for exploiting data obtained from the initial ramp history via a recursion formula is presented. But the method is limited to the case where the loss of relaxation data during that initial time can be a substantial portion of the total (logarithmically measured) time scale.
Abstract: The response of (linearly) viscoelastic material isapproximately the same for ramp and true step strain histories once aninitial time interval of about ten times the ramp-up time has passed.Because the loss of relaxation data during that initial time can be asubstantial portion of the total (logarithmically measured) time scale,a simple method is documented for exploiting data obtained from theinitial ramp history via a recursion formula. Comparison of dataobtained in ramp and relaxation histories are demonstrated to yield goodresults within the accuracy of the test method.
88 citations
01 Nov 1965-Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry
TL;DR: In this paper, a series of experiments were conducted to check the validity of this theory and found excellent agreement with experiment in all cases, however, they are aware that experiments cannot prove a theory and feel strongly that a single integral expression with a nonlinear integrand such as the BKZ elastic fluid equation is sufficient to describe the stress-strain behavior of elastomer.
Abstract: In 1963 Bernstein, Kearsley, and Zapas1 presented a theory of an elastic fluid which gave the correct stress-relaxation response for a large variety of elastomeric materials, including vulcanized rubbers. A principle attractiveness of this theory is its relative simplicity; with a single integral in time, it describes the stress-strain behavior for all types of deformation histories. In the case of simple extension, it predicts the behavior in any uniaxial strain history from the results of single step stress-relaxation experiments which cover the same range of extension and time. We designed a series of experiments to check the validity of this theory and found, as is shown in this paper, excellent agreement with experiment in all cases. We are aware that experiments cannot prove a theory. From our results, however, we feel strongly that a single integral expression with a nonlinear integrand such as the BKZ elastic fluid equation is sufficient to describe the stress-strain behavior of elastomer...
77 citations
TL;DR: In this article, the authors compare two methods of correction to the stress relaxation data obtained after a linear ramp, assuming a relaxation modulus of the form G(t) =Gcffff0 e−(t/τ)β, and show that when the relaxation time is short, there is a substantial error in the Lee-Knauss correction.
Abstract: The material response after the application of a constant strain rate ramp, followed, at time t
1, by a constant strain differs from the response to an ideal (instantaneous) step of strain at short test times. Due to experimental limitations, the ideal step-strain cannot be achieved. As a result, short time stress relaxation data have to be corrected in order to obtain reliable estimates of, for example, the modulus G(t) at times shorter than approximately ten times the ramp time. Here we compare two methods of correction to the stress relaxation data obtained after a linear ramp, assuming a relaxation modulus of the form G(t) =G
0 e−(t/τ)β. The Lee and Knauss correction uses an iterative scheme based on Boltzmann superposition. We compare this method with the Zapas–Craft approach in which the `true' relaxation time becomes t−t
1/2 (t is the experimental time and t
1 is the finite time to apply the step in strain). Our numerical computations show that when the relaxation time is short, there is a substantial error in the Lee–Knauss correction. Although the Zapas–Craft approach provides a better correction for times just slightly greater than t
1/2, it is limited in that it cannot be used for times shorter than t
1/2. We also investigate the case for which the ramp-step is replaced with a more realistic nonlinear function of time. Finally, it is often desirable to have a similar correction for large deformation responses. The Lee–Knauss method is valid only for linear viscoelastic systems whereas the Zapas–Craft approach has not been rigorously evaluated for large deformations. We evaluate the use of the latter for large deformations within the context of the Bernstein, Kearsley and Zapas single integral model.
52 citations